CH4 uptake and its affecting factors in winter wheat field under different stubble height of straw returning

Although the straw returning of maize is a main way of straw utilization, the problem of the ecological cycling agriculture and the maize straw comprehensive utilization was faced. The excessively returning of straw not only affected to the afterreap crop growth but also disadvantaged to protect the ecological environment of farmland. The objective of present study was to estimate the flux of CH4 under the different height stubble of straw returning in the North China Plain and determined the optimization height of stubble to balance of CH4 flux and straw returning. The study based on 10 years of tillage and straw management systems with split-plot design, by used the Static Chamber-Gas Chromatographic method, in which included two tillage methods of zero-tillage (ZT) and conventional tillage (CT), and four treatments of stubble returning were total straw returning (PS), 1 m height stubble returning (S-1), 0.5 m height stubble returning (S-0.5) and no straw returning (AS ). The results showed that, the absorption of CH4 decreased with the increase of straw returning, which was the order of AS≈S-0.5＞S-1≈PS. The modes of tillage have influence on the absorption of CH4 , the flux of CH4 uptake under AC and AZ were higher 18.3% and 15.1% than PC and PZ respectively. The dynamic changes of CH4 absorption were showed three peaks curve in the whole growth period of wheat, it was lowest in over-winter stage, and highest in anthesis stage. The flux in different growth periods of wheat were related with the surface temperature of soil, and the both had a significant positive correlation, but there had a negative correlation with the content of soil organic carbon at a depth of 20 cm in this study. There was no significant correlation between CH4 uptake and soil moisture content. In diurnal variation of CH4 uptake, the fluxes in daytime under PC and PZ were higher 18.2% and 17.7% than in night, and they significant related with the air temperature, soil surface temperature and soil temperature at a depth of 20 cm. CH4 uptake flux under CT was higher 8.65% than ZT. The treatment of 0.5 m stubble height of straw returning under conventional tillage had higher uptake flux of CH4, and the remaining straw was used for other ways, it is a reasonable straw utilization treatment for global warming potential mitigating and straw comprehensive utilization. Therefore, and we suggest that this treatment be developed in this region.